1. Field of the Invention
The present invention relates to an apparatus for impregnating a tube of absorbent material with a flowable material, and more particularly to such a method and apparatus having particular utility in impregnating a porous lamina of such a tube for lining passageways with a subsequently hardening material, the tube being inserted into the passageway after such impregnation, expanded to engage the walls thereof and hardened to form a rigid shell therein.
2. Description of the Prior Art
Methods for lining passageways with a tube having an inner lamina impregnated with a subsequently hardened material are well known and are described in the patents cited in the "Prior Art Statement" below. These methods employ a prefabricated tube and a resin which hardens in a relatively short time at ambient temperature. It the tube is impregnated with the resin when it is formed, it must be refrigerated during storage and shipment to prevent hardening of the resin before the tube is inserted into a passageway which is to be lined. Such refrigeration is relatively inconvenient and expensive, especially when the tube is to be used at a relatively great distance from the location where it is fabricated.
Such refrigeration can be eliminated by impregnating a prefabricated tube at the site of passageway to be lined. In one prior art method for such impregnation, repeated perforations are made along the tube as it is inserted into the passageway for access to the layer to be impregnated. A relatively small portion of the resin required is inserted through each perforation. After each insertion, a patch is applied to the tube over the corresponding perforation. Another method incorporates resin conduits in the tube which extend longitudinally within said layer. This method involves the additional expense of incorporating these conduits and supplying them from a pressurized source of resin. Still another method, which can be used when said layer is disposed interiorly of the tube, is to place a quantity of resin within one end of the tube. Rollers are then manually applied to the exterior of the tube so as to urge the resin to flow along the tube and impregnate the layer. These methods of impregnating such tubes are relatively slow, require considerable manipulation, and do not evenly impregnate the tube with resin. The low speed and excessive manipulation increases the time and expense of impregnation, and the uneven impregnation results in a lining of uneven and, therefore, inferior quality.
Such tubes of the larger sizes are relatively difficult to handle manually due to their weight, especially when loaded with liquid resin. The prior art methods, therefore, are not well adapted to the impregnation of relatively long lengths of such tubing, especially when the tubing is several feet in diameter as is frequently required in the lining of sewers. Such large scale applications of lining passageways with a laminated, resin impregnated tube are highly advantageous, but are severely limited by the prior art.